Display screen or portion thereof with transitional graphical user interface



FIG. 1 is the first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design according to a first embodiment;

FIG. 2 is the second image thereof;

FIG. 3 is the third image thereof;

FIG. 4 is the fourth image thereof;

FIG. 5 is the first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design according to a second embodiment;

FIG. 6 is the second image thereof;

FIG. 7 is the third image thereof; and,

FIG. 8 is the fourth image thereof.

The outer perimeter pair of broken lines in the figures depict a display screen or portion thereof and form no part of the claimed design. The remaining broken lines in the figures depict portions of the transitional graphical user interface and form no part of the claimed design.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-4 and between the images shown in FIGS. 5-8. The process or period in which one image transitions to another image forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 